U.S. patent number 7,739,800 [Application Number 11/585,707] was granted by the patent office on 2010-06-22 for combination blower, trimmer and edger for tending vegetation.
Invention is credited to Bruce K. Bridges, Ryan R. Butrym, Douglas Gaylord, Steven M. Harrington, Edward P. Hurley.
United States Patent |
7,739,800 |
Hurley , et al. |
June 22, 2010 |
Combination blower, trimmer and edger for tending vegetation
Abstract
An engine is connected to the upper end of a drive shaft housing
and a work head with a string trimmer or blower or both is
operatively connected to the lower end of the drive shaft housing
and is rotatably driven by an engine rotating a drive shaft inside
the drive shaft housing and connected to the working head. The
drive shaft housing is rigidly connected to the working head and
may be rotated about its longitudinal axis relative to the engine
in any desired amount of rotation, but the preferred degree of
rotation is 135.degree. to move the working head from a trimming
position with the rotating trimmer string in a horizontal position
to an edging position with the rotating trimmer string in a
vertical position and with the working head being displaced to the
operator's right side for better viewing and control and operator
comfort. In one embodiment, a gear driven crank handle is rigidly
connected to the drive shaft housing and is itself rotated
135.degree. as the drive shaft housing is rotated 135.degree. to
place the handle in a position that is comfortable to use. Further,
the amount of air flowing through the blower is regulated by an air
outlet regulating valve and a separate air intake regulating
valve.
Inventors: |
Hurley; Edward P. (Sarasota,
FL), Harrington; Steven M. (Cardiff, CA), Gaylord;
Douglas (San Diego, CA), Butrym; Ryan R. (Cardiff by the
Sea, CA), Bridges; Bruce K. (Cardiff by the Sea, CA) |
Family
ID: |
39316517 |
Appl.
No.: |
11/585,707 |
Filed: |
October 24, 2006 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20080092398 A1 |
Apr 24, 2008 |
|
Current U.S.
Class: |
30/276; 172/14;
30/122 |
Current CPC
Class: |
A01D
34/905 (20130101) |
Current International
Class: |
A01D
34/46 (20060101); A01D 34/67 (20060101) |
Field of
Search: |
;30/122,276 ;56/12.7
;172/14 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Payer; Hwei-Siu C
Attorney, Agent or Firm: Maxey Law Offices, PLLC Lewellyn;
Stephen Maxey; Brittany
Claims
We claim:
1. A lawn care apparatus comprising: a motor; a clutch housing
connected to said motor for conjoint movement therewith; a throttle
grip housing having a proximal end fixedly connected to said clutch
housing; a drive shaft housing of an elongated tubular shape having
a proximal end inserted into said throttle grip housing for
rotation relative to said throttle grip housing, the proximal end
of said drive shaft housing being abutted against said clutch
housing; a working head attached to a distal end of said drive
shaft housing for conjoint movement therewith; a handle mounted to
said drive shaft housing; a drive shaft extending through said
throttle grip housing and said drive shaft housing, said drive
shaft having a proximal end operatively connected to said motor and
a distal end operatively connected to said working head; said
proximal end of said drive shaft housing and said throttle grip
housing operatively connected to each other by a coupling for
preventing withdrawal of said drive shaft housing from said
throttle grip housing while permitting rotation of said drive shaft
housing relative to said throttle grip housing, whereby said drive
shaft housing is rotatable to position said working head between a
vertical position and a horizontal position without rotating said
motor.
2. The lawn care apparatus of claim 1, wherein said coupling
includes a slot through said proximal end of said drive shaft
housing and about a portion of the circumference of said drive
shaft housing; and wherein said throttle grip housing includes a
rotation guide and limiting stop penetrating said slot.
3. The lawn care apparatus of claim 2, wherein said slot extends
about 135 degrees about the circumference of said drive shaft
housing.
4. The lawn care apparatus of claim 2, wherein said rotation guide
and limiting stop comprises a screw threadably received by a
threaded aperture formed through said throttle grip housing.
5. A lawn care apparatus comprising: a motor; a throttle grip
housing having a proximal end connect to said motor for conjoint
movement therewith; a drive shaft housing of an elongated tubular
shape having a proximal end inserted into said throttle grip
housing for rotation relative to said throttle grip housing; a
working head attached to a distal end of said drive shaft housing
for conjoint movement therewith; a handle mounted to said drive
shaft housing; a drive shaft extending through said throttle grip
housing and said drive shaft housing, said drive shaft having a
proximal end operatively connected to said motor and a distal end
operatively connected to said working head; said proximal end of
said drive shaft housing and said throttle grip housing operatively
connected to prevent withdrawal of said drive shaft housing from
said throttle grip housing while permitting rotation of said drive
shaft housing relative to said throttle grip housing, whereby said
drive shaft housing is rotatable to position said working head
between a vertical position and a horizontal position without
rotating said motor; wherein said drive shaft housing includes a
slot through said proximal end thereof and about a portion of the
circumference of said drive shaft housing; and wherein said
throttle grip housing includes a rotation guide and limiting stop
penetrating said slot; and wherein said rotation guide and limiting
stop comprises a screw threadably received by a threaded aperture
formed through said throttle grip housing.
6. The lawn care apparatus of claim 5, further comprising: a clutch
housing; said throttle grip housing fixedly connected at its
proximal to said clutch housing; and said clutch housing connecting
said throttle grip housing to said motor.
7. The lawn care apparatus of claim 6, wherein said clutch housing
is conical shaped and includes four bosses for attaching said
clutch housing to said motor.
8. The lawn care apparatus of claim 6, wherein said drive shaft
housing is disposed in said throttle grip housing such that the
proximal end of said drive shaft housing abuts said clutch
housing.
9. The lawn care apparatus of claim 5, wherein said handle is
mounted to said drive shaft housing for rotation relative to said
throttle grip housing and said drive shaft housing; and wherein
rotation of said handle causes said drive shaft housing to rotate
relative to said throttle grip housing.
10. The lawn care apparatus of claim 5, wherein said slot extends
about 135 degrees about the circumference of said drive shaft
housing.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
STATEMENT REGARDING A SEQUENCE LISTING
Not applicable.
BACKGROUND OF THE INVENTION
The present invention is related to an apparatus for facilitating
lawn trimming care. More particularly, the present invention
combines a blower inside a housing having an exit blower duct and a
string trimmer head, both driven simultaneously by a motor
connected to a drive shaft. Novel handles facilitate rotating the
apparatus into a trimming mode or an edging mode and air flow
control valves regulate the volume of air flowing through the
blower.
DESCRIPTION OF THE RELATED ART INCLUDING INFORMATION DISCLOSED
UNDER 37 C.F.R. 1.97 AND 1.98
Complete lawn care now typically includes trimming areas that lawn
mowers cannot access easily; edging vegetation along defined
perimeters, such as curbs; and removing the vegetation debris, such
as lawn trimmings or fallen leaves, from areas where they are not
wanted, such as sidewalks and driveways, typically by blowing them
away to an area where they will not be seen, such as the lawn.
Carrying out these separate tasks has traditionally required
different and separate tools, namely, a lawn mower, a string
trimmer, an edger and a blower.
In commercial applications particularly, such as grooming golf
courses, the necessity for using different and separate tools for
these tasks leads to lost time and inefficiency because workers
must return to a tool shed or truck, often located at some distance
from the workers, to retrieve the appropriate tool. A worker may
carry and use a particular tool, for example, a string trimmer, for
several hours without pause, leading him far from his tool shed or
truck. The worker cannot carry all these different tools with him
due to their bulk and weight.
Further, many workers remove the debris shield from string trimmers
to provide a better view of the work area, but the debris shield is
designed to help prevent flying debris from striking the worker in
the eyes or other sensitive areas.
Combining the functionality of some of these separate tools into a
single tool would save time and money, including capital outlay for
the tools.
Further, when a conventional string trimmer is used for edging, the
user typically twists his body into an unnatural, uncomfortable and
dangerous posture and usually walks backward to accomplish edging,
in which the trimmer is held so that the rotating trimming string
rotates basically in a vertical plane. It would be safer to provide
a string trimmer that can be rotated into a natural position that
allows the trimmer string to rotate in a vertical plane.
Some efforts in that direction have been taken. For example, U.S.
Pat. No. 4,773,471 discloses separate operating heads, such as a
string trimmer head or a blower head, that can be attached and
detached from the same power plant and drive train, saving the
expense of a second motor. This system still requires that a
significant subassembly of the tool be removed and replaced by
another tool, requiring the worker to carry separate tools and to
change operating heads on the tool. This system has the same
disadvantages as having separate tools when they are used.
U.S. Pat. No. 4,187,577 discloses a blower chute that can be
strapped onto the bottom of a string trimmer with a bungee cord,
but does not allow the string trimmer function to be used when the
blower attachment is installed, requiring the operator to carry
separate subsystems and install and remove them to carry out the
separate functions of trimming and blowing.
U.S. Patent Application Publication Number US 2002/0007559
discloses a string trimmer with a specially designed shroud that is
supposed to help the rotating string of the string trimmer to
function as a blower. While it has long been known that the
rotating string of the string trimmer provides some blowing forces,
they tend to be non-directional, producing greater drag on the
engine than a small blower would, and even this reference discloses
that any blowing action is basically downward and outward from the
rotating string, which provides little benefit in debris removal
from sidewalks and so forth. Further, any blowing force generated
by the rotating string is minimal and will not move debris any
significant distance.
U.S. Pat. No. 6,442,845 discloses a string trimmer that can be
converted to a blade trimmer and that can be modified to attach a
blower flute or scroll to direct air flow generated by a cooling
fin that is part of the string trimmer spool and designed to cool
the motor of the apparatus. The use of this fan in a attempt to
create a blower function is inadequate because it utilizes a fan
that is designed only for motor cooling and is structurally a part
of a string trimmer head, limiting its utility for actually blowing
debris, due to its position and its use to cool the motor. A string
trimmer head that does not include a cooling fan could apparently
not be used with this device. In addition, reversible cutting
blades pose a greater threat of injury to the operator than a
softer material, such as a trimming string.
Further, many lawn equipment operators use a string trimmer for
basic edging by rotating the handle of the string trimmer so that
the string rotates in a generally vertical plane and the end of the
string strikes the ground adjacent to a sidewalk or the like. To
use a string trimmer in this manner is typically a very awkward
operation that places the motor close to the operator's head and
requires a back bending contortions that are uncomfortable and may
be unsafe. When a conventional string trimmer is turned 90.degree.
more-or-less to present the rotating trimming string in a roughly
vertical plane, the engine naturally rotates along with the drive
shaft and the trimmer head, often moving the piston lower than the
crankcase, allowing excess oil to enter the combustion chamber,
thereby increasing pollution and denying sufficient lubrication to
the piston rod and crankshaft, and this rotation frequently places
the muffler adjacent to the operator's head, which can cause
hearing loss and burns. A string trimmer or the like that could
easily be adjusted to allow comfortable use with the rotating
string in a vertical plane would be a welcome improvement,
especially if it could maintain the motor or engine in its normal
upright position, but none appears to be available, as would a lawn
care apparatus that can be easily adjusted for convenient use by
either a right-handed or a left-handed operator. Further, in some
applications, it may be desirable not to have the blower operating,
which would increase the engine power available to drive the
trimmer string, or to be able to regulate the volume of air
expelled by the blower, independently of the engine throttle or
engine speed.
Utilizing a string trimmer for trimming vegetation, typically
grass, adjacent to curbs, sidewalks, driveways and so forth has
become common. Operators typically rotate the tool in some attitude
designed to turn the rotating string into a basically vertical
plane so that only vegetation immediately adjacent to the
non-vegetation surface is cut. In using the string trimmer as an
edger, the usual goal is to cut the offending vegetation at the
ground, eliminating grass overhang onto the non-vegetation surface.
Twisting a conventional tool to move the rotating string into a
vertical plane leaves the operator contorted into an unnaturally
bend posture, typically with the engine immediately adjacent to his
head, where noise and air pollution are a problem, and the operator
is typically forced to walk backward if he is to see his work,
creating a danger of being hit by passing motor vehicles that he
can neither see nor hear. The electric motor or gasoline engine
also rotates because it is rigidly connected to the drive shaft
housing. In the case of a gasoline engine string trimmer, rotating
the engine can result in crankcase oil finding its way into the
combustion chamber, causing the engine to bog down or stall and
shortening the life of the sparkplug and the engine.
Some string trimmers now have a split boom, or drive shaft housing,
that allows the lower end portion, with the string trimmer
attached, to be removed from the upper boom portion, rotated
90.degree. and then reinserted into the upper boom portion, thus
rotating the string trimmer into a more or less vertical plane. In
order to keep the string trimmer in a vertical plane, however, the
operator must still contort his body into an unnatural and
uncomfortable position and typically must walk backward in order to
see his work.
This outcome when using a conventional string trimmer as an edger
results from the industry's misunderstanding the problem it is
addressing. The industry perceives that the problem is rotating the
trimmer string plane in two-dimensional xz space, that is, moving a
horizontal plane into a vertical plane, that is, a simple
90.degree. rotation clockwise for a right-handed operator or
counterclockwise for a left-handed operator.
In reality, the rotation must be considered in three-dimensional
xyz space because the entire lawn care apparatus is being rotated,
not simply the working head and so the orientation of the drive
shaft housing and handles changes when the cutting head and
rotating string are rotated. If the operator is to comfortably
convert the trimmer for edging with the trimmer string rotating in
a vertical plane, the drive shaft housing must also be rotated in a
fashion that will allows the operator to use a comfortable and
safer posture while edging. The cutting path of the trimming string
is the plane in which the trimming string rotates during use and is
typically either a basically horizontal path when the apparatus is
used for trimming turf or a basically vertical plane or path when
used for edging, in contrast to the walking path, which is the
route or manner of walking, such as forward or backward, that the
operator takes during lawn grooming operations, either trimming or
edging. It is also highly desirable to edge along curbs, sidewalks
and the like while moving toward the interior of the lawn for lawn
trimming chores and then returning over the areas that have been
edged to blow debris back onto the lawn.
Therefore, there is a need for a single lawn care apparatus that
can be used as string trimmer, blower and edger; that will perform
these functions as well as traditional separate tools; that
provides superior trimming as a result of the simultaneous blower
function; that can use a variety of conventional string trimmer
heads; that can be easily adjusted to allow the operator to
comfortably operate the trimming string in a vertical plane without
changing the operator's posture or position through manipulation of
a handle that facilitates comfortable and safe operation of the
string trimmer as an edger and that keeps the motor upright; that
allows the volume of air expelled from the blower to be controlled
and adjusted independently of the engine speed; and that can easily
be adjusted for left-handed or right-handed operators.
BRIEF SUMMARY OF THE INVENTION
Accordingly, it is a primary object of the present invention to
provide a single lawn care apparatus that can be used as string
trimmer, blower and edger.
It is another object of the present invention to provide a single
lawn care apparatus that will perform these functions as well as
traditional separate tools.
It is another object of the present invention to provide a single
lawn care apparatus that provides superior trimming as a result of
the simultaneous blower function.
It is another object of the present invention to provide a single
lawn care apparatus that can use either an internal combustion
engine or an electric motor as a power source.
It is another object of the present invention to provide a single
lawn care apparatus that can use a variety of conventional string
trimmer heads.
It is another object of the present invention to provide a single
lawn care apparatus that can be easily adjusted to allow the
operator to operate the trimming string in a vertical plane without
changing the operator's posture or position through manipulation of
a handle that facilitates comfortable and safe operation of the
string trimmer as an edger and that it keeps the motor upright.
It is another object of the present invention to provide a single
lawn care apparatus that allows the volume of air expelled from the
blower to be controlled and adjusted independently of the engine
speed.
It is another object of the present invention to provide a single
lawn care apparatus that can easily be adjusted for left-handed or
right-handed operators.
To achieve these objects, the present invention includes an
impeller seated in a plenum, preferably a ring plenum, connected to
duct work for blowing, and a string trimmer head, both connected to
a gasoline engine or an electric motor, or other suitable power
source, either corded or battery operated, through a drive shaft
for simultaneous rotation in the same direction. The blower outlet
includes an oval or round shaped outlet nozzle for concentrating
and directing the flow of air from the blower. The rotating string
trimmer creates some draft and the air flow from the blower creates
low air pressure above the rotating string, maintaining the string
along a straighter line and a higher line that would be the case
without the blower's operating and lifting the vegetation to be
trimmed, allowing for more even height of the resulting trimmed
vegetation.
A handle is fixed to the drive shaft housing and allows the
operator to move the handle into a variety of different positions
that allow the operator to use the apparatus with the rotating
string of the string trimmer rotating either a horizontal or
vertical plane without changing his posture or position. The drive
shaft housing tube rotates in its mount adjacent to the engine,
while the handle remains fixed to the drive shaft housing tube and
does not rotate independently of the drive shaft housing tube. The
adjustable handle also allows adjustment of the handle so that the
apparatus to be used by either right-handed or left-handed operator
using the same posture.
Other objects and advantages of the present invention will become
apparent from the following description taken in connection with
the accompanying drawings, wherein is set forth by way of
illustration and example, the preferred embodiment of the present
invention and the best mode currently known to the inventors for
carrying out their invention.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
FIG. 1 is an isometric view of a combination blower, trimmer and
edger for tending vegetation (lawn care apparatus) according to the
present invention shown in use for trimming and blowing and
utilizing a three-lobed handle on a straight-shaft lawn care
apparatus for facilitating transition of the lawn care apparatus
from a trimming to an edging mode.
FIG. 2 is an isometric view of the lawn care apparatus of FIG. 1
illustrating the lawn care apparatus in use for edging, which is
accomplished by rotating the three-lobed handle about 135.degree.
counterclockwise from the point of view of a right-handed person
using the lawn care apparatus, which rotates the drive-shaft
housing and working head, but not the engine.
FIG. 3 is an isometric view of the lawn care apparatus of FIG. 1
illustrating the lawn care apparatus in use for edging, which is
accomplished by rotating the three-lobed handle 135.degree.
clockwise from the point of view of a left-handed person using the
lawn care apparatus, which rotates the drive-shaft housing and
working head, but not the engine.
FIG. 4 is an isometric view of a handle assembly adjacent to the
engine and partially cut away to reveal the drive shaft rotation
mechanism.
FIG. 5 is an enlarged fragmentary isometric view of the proximal
portion of the handle assembly of FIG. 4.
FIG. 6 is an exploded enlarged fragmentary view of the handle
portion shown in FIG. 5.
FIG. 7 an exploded fragmentary isometric view of the distal end
portion of the handle assembly of FIG. 4.
FIG. 8 is a fragmentary isometric view of the distal end portion of
the handle assembly of FIG. 4 as shown in FIG. 7 shown
assembled.
FIG. 9 is a side view of the lawn care apparatus of FIG. 1 that
utilizes an alternative embodiment of a handle for rotating the
drive shaft housing independently of the engine of the lawn care
apparatus.
FIG. 10 is an isometric lower end view of a lawn care apparatus
according to the present invention and alternative handle
embodiment of FIG. 9 illustrating the rotation of the alternative
embodiment handle of FIG. 9.
FIG. 11 is an isometric view of the alternative embodiment handle
of FIG. 9 shown in the position the handle is in during trimming,
that is, with the trimmer string rotating in a basically horizontal
plane.
FIG. 12 is an isometric view of the alternative embodiment handle
of FIG. 9 shown in the position the alternative embodiment handle
is in during edging, that is, with the trimming string rotating in
a basically vertical plane.
FIG. 13 is an exploded isometric view of the alternative embodiment
handle of FIG. 9.
FIG. 14 is a bottom view of the housing of the alternative
embodiment handle of FIG. 9.
FIG. 15 is a front view of an air shut-off control lever handle for
controlling the air flow through the blower of the lawn care
apparatus of FIG. 1 by means of a cable running through the drive
shaft housing.
FIG. 16 is a side view of the air shut-off control lever handle of
FIG. 15.
FIG. 17 is a cross sectional view taken along lines 17-17 of FIG.
14 showing the arrangement of the gears inside the gear housing of
the alternative embodiment handle of FIG. 9.
FIG. 18 is a top view of the blower and trimmer working head of the
lawn care apparatus of FIG. 1.
FIG. 19 is a cross section taken along lines 19-19 of FIG. 18
showing the butterfly air flow cut-off valve in the outlet duct of
the blower of the lawn care apparatus of FIG. 1.
FIG. 20 is a fragmentary isometric view of the blower and blower
air outlet duct showing the butterfly air cut-off valve in the
outlet duct of the blower in the closed position, shutting off the
flow of air and partially cut away to reveal the blower inside the
blower housing.
FIG. 21 is an isometric view of the air outlet shut-off valve
control lever for use with the lawn care apparatus of FIG. 1
showing the control lever in the position it is in when the
butterfly air inlet shut-off valve in the open position, allowing
air to be blown out of the blower nozzle readily during
operation.
FIG. 22 is an isometric view of the air outlet shut-off valve
control lever for use with the lawn care apparatus of FIG. 1
showing the control lever in the position it is in when the
butterfly air inlet shut-off valve in the closed position,
preventing air from being blown out of the blower nozzle readily
during operation.
FIG. 23 is a top view of the blower housing and shield assembly of
a lawn care apparatus according to the present invention showing an
air inlet valve and attached control handle, with the air inlet
valve shown in the open position, allowing air to be drawn into the
blower when the blower is turning.
FIG. 24 is a top view of the blower housing and shield assembly of
a lawn care apparatus according to the present invention showing an
air inlet valve and attached control handle, with the air inlet
valve shown in the closed position, substantially depriving the
blower of intake air.
FIG. 25 is a top view of the air inlet valve and control handle of
FIGS. 23, 24.
FIG. 26 is a user's top view of a lawn care apparatus according to
FIG. 1 having the alternative embodiment handle of FIG. 9
illustrating the position of the handle when the lawn care
apparatus is used for trimming by a right-handed operator, that is,
with the trimming string rotating in a basically horizontal plane
when used in a right-handed user position being manipulated into a
position suitable for use by a left-handed operator.
FIG. 27 is a user's top view of a lawn care apparatus according to
FIG. 1 having the alternative embodiment handle of FIG. 9
illustrating the position of the handle when the lawn care
apparatus is used for edging, that is, with the trimming string
rotating in a basically vertical plane when used in a left-handed
user position.
FIG. 28 is a user's top view of a lawn care apparatus according to
FIG. 1 having the alternative embodiment handle of FIG. 9
illustrating the position of the handle when the lawn care
apparatus is used for trimming, that is, with the trimming string
rotating in a basically horizontal plane when used in a left-hand
user position.
FIG. 29 is an enlarged fragmentary view of the handle of FIG. 9
connected to the gear box housing of the handle of FIG. 9
illustrating one embodiment of a stop mechanism for controlling
rotation of the handle.
FIG. 30 is a stylized front view of the gear-driven crank handle
rotation system of FIGS. 11-13 utilizing an alternative embodiment
of the rotation stop system best seen in FIG. 29 showing the
gear-driven crank handle rotation system of FIGS. 11-13 of the lawn
care apparatus of FIG. 9 locked into position for trimming for a
right-handed user.
FIG. 31 is a cross section taken along lines 31-31 of FIG. 30.
FIG. 32 is a stylized front view of the gear-driven crank handle
rotation system of FIGS. 11-13 utilizing an alternative embodiment
of the rotation stop system best seen in FIG. 29 showing the
gear-driven crank handle rotation system of FIGS. 11-13 of the lawn
care apparatus of FIG. 9 locked into position for trimming for a
left-handed user.
FIG. 33 is a cross section taken along lines 33-33 of FIG. 32.
FIG. 34 is a sectional front end view of the main body portion of
the gear driven crank handle system mounted on the drive shaft
housing shown in condition for free rotation about the drive shaft
housing.
FIG. 35 is an enlarged fragmentary exploded isometric view of the
joint mechanism between upper and lower drive shaft housing
members, allowing for different working heads to be used
interchangeably with the same upper drive shaft housing portion and
engine.
FIG. 36 is a schematic side view of the lawn care apparatus of FIG.
1 shown oriented in an xyz coordinate system.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1, a combination blower, trimmer and edger for
tending vegetation, that is, a lawn care apparatus, 10 according to
the present invention includes an elongated tubular drive shaft
housing 12 having a lower, or distal end 14 with a working head 16
attached to it and an upper, or proximal end, 18 having a motor 20
connected to it. The motor 20, which may be either a gasoline
engine of four stroke or two-stroke design, or an electric motor,
or other suitable power source, which may be battery powered or
powered by conventional AC power through a cord, rotates a drive
shaft housed within the drive shaft housing 12, which is a straight
shaft tool as shown in FIGS. 1-3.
Still referring to FIG. 1, the straight shaft version of FIGS. 1-3
is preferred in commercial turf applications because there is less
friction between the drive shaft splines and the drive shaft sleeve
inside the drive shaft housing, resulting in lower operating
temperatures inside the drive shaft housing and longer life. In
order for the lawn care apparatus 10 with the straight shaft 12 to
present the working head 16 to horizontal turf when the lawn care
apparatus is held in a normal position, the angle of direction of
the driving forces must be changed, which is accomplished by the
two-gear transmission 22, which conventionally reduces the
revolutions per minute (rpm) of the rotating string 24 to one-half
of the rpm of the engine 20, and reverses the direction of rotation
of the rotating string 24 relative to the engine 20 and doubles the
torque applied to the rotating string 24. The transmission 18
itself generates enough heat to burn the user, but reduces the
temperature of the drive shaft. The transmission 18, however, adds
significantly to the cost of the overall lawn care apparatus 10, so
in light-duty, typically consumer applications, a bent drive shaft
housing, such as that shown in FIGS. 9, 10, allows the working head
16 to be oriented at basically 90.degree. to the portion of the
drive shaft housing that it is connected to and eliminates the two
gear transmission 22, saving the manufacturer money, but providing
a tool with a shorter life. Further, however, the increased
friction created by bending the drive shaft heats the drive shaft
housing sufficiently to burn the user and heats the internal
plastic spline that houses the drive shaft enough to shorten its
life significantly. The present invention is adaptable for use with
either a straight shaft lawn care apparatus 10 or a curved shaft
lawn care apparatus 10.
Still referring to FIG. 1, the rotating crankshaft of the motor 20
is typically connected to a clutch, which drives the proximal end
91 of a drive shaft or cable 90 (see, e.g., FIG. 4, 6), which in
turn is operatively connected at its distal end 25 to a working
head 16, such as the string trimmer head 26. In each embodiment, a
drive shaft 90 has a proximal end 91 operatively connected to the
engine 20 and a distal end 25 operatively connected to a working
head 16. A mounting flange 32 is used to mount a shield, such as
the shield of FIGS. 9, 10, which has been omitted from FIGS. 1-3 to
show the working head 16 more clearly. A human operator who is
right-handed, grasps a throttle handle grip, or sleeve, 34, which
is adjacent to the lower end of the motor 20, which is fixed onto
an upper portion of the drive shaft housing 12, in his left hand
and operates the throttle control trigger 36 with his left-hand
index finger. In this position, the gasoline tank cap 38 is located
furthest toward the right-hand margin of the drawing, and is
physically higher than the gasoline tank.
Orientation of the directional terms left-hand, right-hand,
clockwise and counterclockwise is determined from the point of view
of a person standing adjacent to the engine 20 and facing the
working head 16.
Still referring to FIG. 1, the operator grasps the three-lobed
handle 40 with his right hand. The three-lobed handle 40 includes a
top lobe 42 having a top hand grip 44, which is slightly curved but
substantially straight and includes a finger opening 46. The top
lobe 42 is the portion of the three-lobed handle 40 closest to the
operator when the lawn care apparatus 10 is used for trimming and
blowing along a substantially horizontal surface, as shown in FIG.
1. In this trimming and blowing mode shown in FIG. 1, the top lobe
42 is naturally presented to the operator for gripping and no other
portion of the three-lobed handle 40 can be comfortably gripped.
The three-lobed handle 40 is preferably made in two pieces from
injection molded plastic, including an primary section 50 and a
fastening section 52 that are fastened together by screws. The
three-lobed handle 40 is fixed to the drive shaft housing tube 12
so that these parts can only rotate together, that is, the
three-lobed handle 40 does not rotate independently of the drive
shaft housing tube 12.
Still referring to FIG. 1, a left-hand lobe 54 and the right-hand
lobe 56 are connected by and both include an arcuate hand grip
portion 58 having a large finger opening 60 along its length. The
left-hand lobe 54 is further connected to the top lobe 44 by the
left-hand spoke 55 and the right-hand lobe 56 is further connected
to the top lobe 44 by the right-hand spoke 57. The fastening
section 52 is actually screwed into the area where the left-hand
spoke 55 and the right-hand spoke 57 join in the middle of the
distances between the perimeter point where each begins to the
approximate center of the three-lobed handle 40. When the lawn care
apparatus 10 is in the trimming position shown in FIG. 1, neither
the left-hand lobe 54 nor the right-hand lobe 56 can be gripped
comfortably due to the hump 59 on either side of the top lobe 42
that forces the operator to move the three-lobed handle 40 into a
comfortable gripping position, which is also the desired position
for a particular use, e.g., trimming or edging. Left and right are
taken from the position of a person standing behind the motor 20
and facing the lawn care apparatus 10 with the working head 16
directly in front of the person. Clockwise and counterclockwise are
defined from the point of view of the this same reference
person.
Referring to FIG. 2, the three-lobed handle 40 and the drive shaft
housing 12 have been rotated together exactly 135.degree.
counterclockwise from the position shown in FIG. 1, which places
the rotating string 24 into a substantially vertical plane, as
shown, while the motor 20 remains in the same position as shown in
FIG. 1, that is, with the gasoline tank cap 38 being the portion of
the motor 20 that is closest to the right-hand drawing margin. The
stationary upright position of the motor 20 is accomplished by
allowing the drive shaft housing 12 to slip about a sleeve at its
proximal end adjacent to the motor 20, an arrangement discussed in
detail in relation to FIGS. 4-8. The ability to retain the motor 20
in a stationary upright position ensures that the motor 20 remains
in its desirable operating normal basically upright position, that
is, with its crankcase lower than the piston and with the exhaust
pipe away from the operator's face. This 135.degree.
counterclockwise rotation, as indicated by the directional arrow 62
also presents the right-hand lobe 56 for comfortable gripping and
this rotation is used for by a right-handed operator. This rotation
also moves the working head 16 out to the right side of the
operator somewhat, allowing the operator to work comfortable while
moving forward, allowing him to view the work area easily and to
see oncoming motor vehicle traffic.
Still referring to FIG. 2, in common practice operators remove the
shield from a straight shaft trimmer, thereby removing the string
cutting tool and they allow the trimmer string 24 to become very
long, for example 0.6-1 m (2-3 feet) in order to see the end of the
trimmer string 24 better. The longer trimmer string places extreme
loads on the engine 20 and the bearings. Further, it basically
converts the rotation of the trimmer string 24 from a horizontal
plane to a horizontal plane into a two dimensional rotation problem
rather that a three dimensional rotation problem because the
apparatus 10 resembles a long axis cutting tool such as a chainsaw.
In this case, a rotation of the drive shaft housing 12 of about
90.degree. serves to convert the apparatus 10 from a trimming mode
to an edging mode.
Referring to FIG. 3, the lawn care apparatus 10 has been similarly
rotated, but 135.degree. clockwise, as shown by the directional
rotational arrow 64, which is the direction of rotation for a
left-handed user, who will naturally grip the throttle handle grip
34 with his right-hand and the now presented left-hand lobe 54 of
the three-lobed handle 40 with his right hand. The motor 20 remains
in its normal basically upright position as described in relation
to FIG. 2 above, with the working head 16 being projected somewhat
to the left of the left-handed user, allowing him comfortably to
walk forward while edging and to view both the work area and
oncoming traffic while the rotating string 24 rotates in an
essentially vertical plane, as shown in FIG. 3.
Referring to FIG. 4, the throttle grip housing 34 is fixedly
connected at its proximal end 66 to a conical shaped clutch housing
68, which has four bosses 70 for attaching the engine 20. The
throttle grip housing 34 is formed from a right-hand shell member
72 and a mating left-hand side shell member 74 (FIG. 1) that are
fastened together by tightening screws into the screw fittings 76,
creating a top seam 78 and a bottom seam 80. The throttle grip
housing 34 is shown with a top and bottom seam 78, 80 for purposes
of clarity and this construction is commonly in the art, but it is
preferable to provide seams on the left-hand a right-hand sides of
the throttle grip housing 34 so that when the user grasps the
throttle grip housing 34 there is no chance that the seams will
open up, which can pinch the user's hand. The drive shaft housing
12 is inserted into the hollow body of the throttle grip housing 34
so that its proximal end 82 abuts the clutch housing 68. The drive
shaft housing 12 is firmly seated in the throttle grip housing 24,
but can be rotated inside it by firmly twisting the drive shaft
housing 12 relative to the throttle grip housing 34. The engine 20
is fixed to the clutch housing 68 and the working head 16 is
fixedly connected to the distal end of the drive shaft housing 12,
so when the drive shaft housing 12 is twisted relative to the
throttle grip housing 34, the working head 16 rotates with the
drive shaft housing 12 and the engine 20 does not. This arrangement
works in the same fashion with either a curved shaft of straight
shaft lawn care apparatus 10.
Still referring to FIG. 4, to limit the rotation of the drive shaft
housing 12 and to prevent it from being unintentionally removed
from the throttle grip housing or sleeve 34, a limiting slot 84 is
formed into the drive shaft housing 12 immediately adjacent to its
distal end, about a portion of the circumference of the drive shaft
housing 12 and a rotation guide and limiting screw or other stop
member 86 is inserted into a threaded aperture 88 in the bottom of
the throttle grip housing and fixed therein so that the rotation
guide and limiting screw 84 penetrates the limiting slot 84. The
rotation guide and limiting screw 84, or other suitable limiting
stud or the like, must be short enough so that it does not
interfere with the drive cable or drive shaft 90 and guides the
rotation of the drive shaft housing 12 to prevent the drive shaft
housing 12 from being pulled free from the engine 20, slipping
downward, or so forth, which may cause drive failure. Proximal end
91 of the drive shaft or drive cable 90 is connected to the engine
20, and may be operatively connected to a clutch between the engine
20 and the proximal end 91.
Still referring to FIG. 4, the throttle control trigger 36 include
a pivot point peg 92 fastened into the throttle grip housing 34 and
an aperture 94 that receives a hooked end 96 of the throttle cable
98, with hooked proximate end 100 of the throttle cable 98 being
inserted into a corresponding aperture on the throttle of the
engine 20.
Referring to FIG. 5, the left-hand end 102 of the limiting slot 84
stops counterclockwise rotation of the drive shaft housing 12 as
shown by the counterclockwise rotational directional arrow 104 when
it butts into the limiting screw 86 and the right-hand end 106 of
the limiting slot 84 stops clockwise rotation of the drive shaft
housing 12 when it butts into the limiting screw 86 when rotated
clockwise as shown by the clockwise rotational directional arrow
108. Total rotation allowed by the limiting slot lies in a range of
110.degree.-160.degree., with the strongly preferred range of
rotation being 135.degree., as shown enlarged in FIG. 6. The
rotation of the drive shaft housing 12 independently of the
throttle handle grip 34 and the engine 20 is utilized by the lawn
care apparatus 10 with the three-loped handle 40 of FIG. 1, the
crank operated gear driven handle of FIG. 9, or any other type of
handle.
Referring to FIG. 7, an alternative embodiment throttle handle grip
110 formed from an upper clamshell half 112 and a mating lower
clamshell half 114 fastened together by adhesives or other suitable
fasteners to clamp the drive shaft housing 12 firmly while still
permitting rotation of the drive shaft housing 12 independently of
the throttle handle grip 110 utilizing the slot 84 mechanism
described above. A set screw 116 is inserted through an aperture in
a cam lever lock 118 and is received and tightened into the
threaded aperture 120 in the upper clamshell half 112. A cam
surface 122 on the cam lever lock 118 is pressed against a cam
receiving fitting 124 in the aperture 126 in the lower clamshell
have 114 such that when the cam lever handle 128 is turned in the
direction of the arrow 1140 (FIG. 8), the upper and lower
clamshells 112, 114, the upper and lower clamshells 112, 114, are
clamped together firmly enough that the drive shaft housing 12
cannot be rotated within the throttle handle grip 110 with normal
effort, that is, the drive shaft housing 12 is locked into the
rotated position it was set to prior to turning the cam lever 128.
To release or unlock the cam 120 and allow rotation of the drive
shaft housing 12 relative to the throttle handle grip 110 again,
the cam lever 128 is turned in the opposite direction as shown by
the arrow 130 in FIG. 7.
Still referring to FIG. 7, each clamshell half 112, 114, includes a
plurality of upstanding reinforcing ribs 132, each having a concave
curved surface 134 that defines a semi-circle and that grip the
drive shaft housing 12 when the upper clamshell half 112 and the
lower clamshell half 114 are joined together as shown in FIG. 8 and
a flat left-hand flange portion 136 and a flat right-hand flange
portion 138. These reinforcing ribs strengthen the throttle handle
grip 110 and dampening vibrations in the drive shaft housing 12
during operation.
Referring to FIG. 8, the assembled throttle handle grip 110 is
illustrated, showing the locking action of the cam lever lock
118.
Referring to FIG. 9, a gear-driven crank handle shaft rotation
system 142 (crank handle system) is mounted onto the drive shaft
housing 12 in the same fashion as the throttle handle grip 110 of
FIG. 8, 9 and is located below the throttle grip 34 or 110 and at
the approximate longitudinal center of gravity. The crank handle
system 142 includes a housing 144 and a handle 146 protruding from
the housing 144. When the lawn care apparatus 10 is in the trimming
position, that is with the trimming string 24 and the debris shield
148 basically horizontal, the grip portion 150, which is covered by
the high-friction rubber comfort grip 151 (best seen in FIG. 10) of
the handle 146 is horizontal while the extension arm portion 152 of
the handle 146 projects upward from the drive shaft housing 12 and
is basically perpendicular to it. The housing 144 has a two-piece
clamshell structure that grips the drive shaft housing 12 (e.g.,
FIG. 13) firmly enough that the drive shaft housing 12 rotates with
it, that is, the housing 144 and the connected crank handle 146
cannot turn independently of the drive shaft housing 12, while the
drive shaft housing 12 can rotate independently of the engine 20
using the structure shown in FIGS. 4, 5, discussed above.
Still referring to FIG. 9, a blower housing 154 enclosed a ring
blower, or impeller, 155 that is operatively connected to the
distal or lower, end 14 of the drive shaft housing 12 and includes
an air outlet duct 156 having a top wall 158 and a bottom wall 160,
which are closer together at the outer edge 162 of the air outlet
duct 156, that at the blower housing 154, as are the left-hand side
wall 164 and the right-hand side wall 166 (FIG. 10) of the air
outlet duct 156, providing a nozzle with a venturi effect that
accelerates the air moving through the air outlet duct 156 as it
passes through the nozzle or air outlet duct 156. The ring blower,
or impeller, 155 is superior to the commonly used volute or spiral
blower because the ring blower, or impeller, 155 occupies a smaller
volume, while maintaining high velocity and high volume air flow,
thereby not interfering with the trimmer string 24 or the
operator's sight lines. The same constricted nozzle design is
retained regardless of the general shape of the air outlet duct,
which may be conical, oval, etc.
Still referring to FIG. 9, a the point 170 defines the origin of a
three dimensional space conveniently plotted as the xyz space 171
and defines the center of the trimmer string 24, with a first
portion 172 and a second portion 174 having equal lengths and
spanning a total distance from the first portion tip 176 to the
second portion tip 178 preferably lying in a range of about 30-76
cm (12-30 inches), with the preferred length being 43 cm (17
inches). The trimmer string 24 may be one length of string as
utilized in some types of string trimmer heads or two separate
lines as shown in, for example, FIG. 9, or more than two separate
strings. During operation, all strings will be cut to equal length
because the debris shield 148 includes a line cutter.
Still referring to FIG. 9, the air outlet duct 156 and its outlet
edge 162 are aimed downwardly to direct the air flow at the outer
tip ends 176, 178 of the trimmer string 24, thereby increasing and
maximizing the debris dispersion capability of any particular lawn
care apparatus 10 for any given size of motor or engine 20 and
reducing or eliminating the lift imparted to the rotating string 24
by air blowing over the trimmer string 24. When the outlet nozzle
is parallel to the trimmer string 24, the lift imparted due to
Bernoulli's principle is considerable, causing the rotating trimmer
string to depart from its otherwise planar rotation, thereby
placing excess strain on bearings and the like, wasting engine
power, decreasing the effectiveness of the trimming function and
reducing operator control over the height of the cut being
made.
Referring to FIG. 10, the handle 146 includes a stem portion 180
that protrudes from the housing 144 of the crank handle system 142
and is connected to a gear inside the housing 142, as described
below. The stem portion 180 can be rotated about its own
longitudinal center line from its neutral equilibrium position
shown in FIG. 9 in either a clockwise direction (as seen from a
position looking down on the stem portion 180) as shown by the
arrow portion 182 or clockwise (as seen from a position looking
down on the stem portion 180) as shown by the arrow portion 184 of
the double-headed directional arrow 186, which allows a total
rotation of the stem portion 180 in a range of
105.degree.-165.degree., with the preferred rotation being
135.degree., with one-half of any rotation being clockwise of the
equilibrium or neutral position and one-half of any allowed
rotation being counterclockwise of the neutral position.
Still referring to FIG. 10, the stem portion 180 has been rotated
135.degree. in the direction indicated by the directional arrow 188
in FIG. 9, that is, by the operator's pulling the handle grip 151
back toward himself, thereby rotating the rotating string 24 into a
vertical plane on the user's left-hand side, resulting in the
handle 146 being rotated into the position shown in FIG. 10, while
maintaining the engine 20 in its normal upright position. With the
handle 146 in the position shown, the string trimmer head 26 is
also moved outward to the user's left side, thereby allowing the
operator to hold the lawn care apparatus 10 in a natural position
substantially identical to the position used for trimming in a
horizontal plane and allowing the operator to walk forward while
edging and easily maintaining a straight line that he can see
throughout the operation, while also seeing oncoming traffic.
Referring to FIG. 11, the housing 144 includes a locking set screw
190 that permits easy manipulation of the rotating handle 146 when
loosened and locks the handle 146 into its desired position when
tightened. As shown, the handle 146 is in its normal position for
trimming, with the rubber grip 151 above the housing 144.
Referring to FIG. 12, the handle 146 has been rotated about the
stem portion 180 in the direction of the directional arrow 192 by
135.degree. to rotate the housing 144 toward the viewer by
90.degree., presenting the bottom surface of the housing 144 as the
portion of the housing 144 closest to the viewer. Since the working
head 116 is rigidly connected to the drive shaft housing 12 and,
through it, the housing 144, the working head 14 has also been
rotated 90.degree., as shown in FIG. 10. This rotation of the
housing 144 also exposes to view the air flow shut-off control
lever 194, which is connected to the housing by the rivet 196,
allowing the operator to move the control lever 194 between an on
position and an off position or any intermediate position through a
cable 198, which may be run along the outside of the drive shaft
housing, or, in the case of a non-split boom tool, inside the drive
shaft housing, and shut off valve system shown in detail in FIGS.
20-21. This air shut off valve allows the user to select the
desired volume of air expelled from the blower housing 154.
Referring to FIG. 13, the stem portion 180 includes a proximal end
198 that is fastened to stop member collar 200 and then to a first
45.degree. beveled gear 202 having an access parallel to the stem
180 and which meshes with a mating second 45.degree. beveled gear
204 that is rigidly mounted onto the drive shaft housing 12, which
passes through the hole 206 in the mating 45.degree. beveled gear
204. Each beveled gear 202, 204 is molded from tough durable nylon
and has thirty-three teeth, or other 1:1 gear ratio, so that
turning the stem portion 180 resulting in a 1:1 rotation of the
drive shaft housing 12. Rotation of the stem portion 180 is limited
by the stop collar disk 205, which includes a recessed land portion
207 that extends over 135.degree. of the stop disk 205, with the
stop rod 211, fastened to the stem portion 180, bumping into the
resulting upstanding flange portion 209 at either end of the
allowed range of rotation, as discussed in more detail below in
connection with FIG. 29.
Still referring to FIG. 13, the housing 144 includes an upper
clamshell member 208 and mating lower clamshell housing member 210
that form a horizontal seam 212 when clamped together by the rear
set screw 214 and the forward set screw 216, and to conceal and
protect the two beveled gears 202, 204. Each clamshell member 206,
208 includes about twelve upstanding reinforcing rib portions 218,
each having a semi-circular recess portion 220 that fits against
the outer surface of the circular cross section drive shaft housing
12 firmly to hold the housing 144 firmly against the drive shaft
housing 12. The midpoint of the semi-circular recess of each
reinforcing rib portion 218 is in the center of the distance
between the outer edges of the width of the clamshells 208, 210.
Each reinforcing rib portion 218 also includes a left and right
hand flat outer flange portions 222. These portions are aligned
with one another on the upper and lower clamshell members 208, 210
and contact each other when the two clamshells 208, 201 are brought
together. The reinforcing rib portions 218 strengthen the housing
144 and dampening vibrations in drive shaft housing 12 during
operation, increasing operator comfort and reducing the likelihood
of carpal tunnel syndrome in operators. Three stem housing ribs 224
perform the same functions in the stem housing portion 226 of the
housing 144 that extends outwardly and perpendicularly to the main
housing body 228 to provide support for the stem 180 portion of the
handle 146.
Still referring to FIG. 13, the throttle-like air valve control
lever 194 is held in the bracket 230, which includes a circular lid
portion 232 and a stem-like fastening portion 234 that is fastened
to the housing 144 by screws or the like.
Still referring to FIG. 13, the length of the extension arm portion
152 of the handle 146 can be adjusted to accommodate comfortably
different height operators by pressing the spring release button
236, thereby releasing a spring-loaded locking button that is
seated in a selected one of the adjustment apertures 238 in an
outer end portion 240 of the extension arm portion 152. The
proximal end 242 of the outer end portion 240 is received into the
cylindrical coupling member 244 and can be set in its desired
length by the operator. The lower end portion 246 includes a distal
end 248 that is received into and rigidly fixed to the cylindrical
coupling member 244 and the outer end portion 240 fits inside the
lower end portion 246, which has a slightly larger diameter. This
adjustment mechanism allows comfortable upright operating postures
for virtually any height operator.
Still referring to FIG. 13, the angle between the grip portion 150
and the outer end portion 240 of the handle 146 is 90.degree. as
indicated by the double-headed arcuate arrow 2239 and both of these
parts of the handle lie in the same plane, that is, it is formed by
bending a tube 90.degree. at the appropriate point. The angle
between the stem portion 180 and the lower end portion 240 of the
handle 146 is 110.degree. (?) As indicated by the double-headed
arcuate arrow 241.
Referring to FIG. 14, the throttle-like air control lever 194 can
be adjusted at any point along an arc of 105.degree. as indicated
by the double-headed arrow 250 from the fully closed position 252
to the fully open position 254.
Referring to FIG. 15, the throttle-like air control lever 194 can
be set into a plurality of discrete positions by setting one of the
indexing apertures 256 formed into the circular control plate 258
that is connected to the air control lever 194. The indexing
apertures 256 set over a small setting nub in the lid portion 230
of the bracket 230.
Referring to FIG. 17, a compressed coil spring 260 applies force to
the circular control plate 258, keeping the throttle-like air
control lever 194 in the desired position set by the operator.
Referring to FIG. 18, an open web 262 of air inlet openings 264
allows air to be drawn into the top of the blower housing 154 when
the blower, or impeller 155 is rotating, which is expelled through
the air outlet duct 156. The open web 262 allows for vigorous air
flow, while preventing debris, such a sticks, from being drawn into
the blower housing 154, which might otherwise be hurled
dangerously. The debris shield 148 preferably includes an outer
arcuate perimeter 263 and a pair of outer wing portions 265, which
block additional debris and are outside the width of the fan
portion 267 that becomes progressively narrower as it comes closer
to the blower housing 154, to which it is connected.
Referring to FIGS. 19, 20, the throttle-like air flow regulating,
or control, valve 266, set into the outer edge of the air outlet
duct 156 and retained by the pins 270, is urged by the spring 268
into the closed position shown in FIG. 20, in which the outlet
opening in the air outlet duct 156 is substantially blocked. When
the operator pulls on the cable 197, the throttle-like air flow
control valve 266 is progressively opened, until the butterfly
valve portion is essentially parallel to the upper and lower walls
158, 160 of the outlet duct or nozzle 156, maximizing air flow
through the blower housing 154. Alternatively or simultaneously,
the air flow through the blower housing 154 may be progressively
reduced or increased or essentially shut off by a valve mechanism
at the air inlet open web 262, as shown in FIGS. 23-25 and
discussed below.
Still referring to FIG. 19, shows the throttle-like air flow
control valve 226 in the closed position, substantially shutting
off the air flow, which is accomplished by rotating the
throttle-like air flow control valve 226 in the direction of the
arrow 274 by pulling on the cable 197 sufficiently to overcome the
tension of the spring 268. Letting off on the cable 197 allows the
spring 268 to move the throttle-like air flow control valve 226 in
the direction of the arrow 276, thereby progressively and
selectively opening the control valve 226.
Decreasing the air flow through the blower 155, through
manipulating the valve 266 or a valve in the open web 262, or both,
increases the proportion of engine 20 power available to drive the
trimmer string 24 because the work being performed by the blower,
or impeller, 155 is reduced, as is the volume of air passing
through the blower, or impeller, 155. This effect is maximized when
the air flow through the blower, or impeller, 155 is substantially
closed off. Even with the air flow control valve 266 in the fully
closed position, however, some air is moved by the blower, or
impeller, 155, which draws air through the hollow tubular drive
shaft housing 12, cooling it, thereby preventing overheating and
extending the life of the drive shaft cable 90 and associated
bearings or sleeves. In curved shaft string trimmers, heat buildup
in the general area of the curve in the drive shaft housing is
conducted to a spool of plastic trimmer string and heats the
trimmer string enough to partially melt it, welding the reserve
supply of trimmer string to itself, a common and aggravating
problem wholly overcome by the blower, or impeller, 155 as
described.
Referring to FIG. 20, a guard bracket 278 includes an outer guard
portion 280 connected at one end to a left-hand leg portion 282 and
a right-hand leg portion 284 which are substantially parallel to
one another and substantially perpendicular to the outer guard
portion 280 and each of which includes an inwardly projecting
fastening end portion 286, that snap into aligned apertures in the
air outlet duct 156. The guard bracket 278 helps protect the air
outlet duct 156 from damage from dragging or banging, which is more
likely when the lawn care apparatus 10 is used for edging by a
left-handed operator, which results in the air outlet duct 156
being close to the ground and therefore susceptible to damage. The
guard bracket 278 is preferably made from heavy gauge spring
steel.
Referring to FIG. 21, in an alternative air-flow valve control
lever for opening, closing or setting an intermediate opening of
the throttle-like air flow control valve 266, a pivoting handle 288
is connected to the drive shaft housing 12 by the clamshell bracket
290, which is secured by the nut and bolt 292. The cable 197 has a
ball fitting 294 in its end, which locks the cable 197 into the
cable lock aperture 296 on the handle 288. In this embodiment, the
cable 197 runs along the outside surface of the drive shaft housing
12, which is necessary when the lawn care apparatus includes a
split boom construction that allows different working heads 16 and
attached lower boom portions to be connected to the same upper boom
portion and engine, as shown in FIG. 30. The throttle-like air shut
off valve 266 is in the closed position when the handle 288 is in
the position shown in FIG. 21 and is allowed to be opened by spring
force when the operator pulls back toward himself in the direction
of the arrow 298 in FIG. 22, causing the cable 197 to go slack.
Referring to FIGS. 23-25, an air inflow regulating, or control
valve, 300 in the top 302 of the blower housing 154 includes seven
fan shaped blades 304 each having a narrow end connected to a
circular hub 306 having an aperture 308 in its center. An elongated
control handle 310 is connected to the fan shaped blade 312, which
allows the air inflow control valve 300 to be rotated easily.
Adjacent to a proximal end 314 of the control handle 310 includes a
locking slot 316 that locks the air inflow control valve 300 into
the operators desired position when it any of the indexing nubs 318
on the top surface 320 of the debris shield 148 penetrates the
locking slot 316.
As shown in FIG. 23, the air inflow control valve 300 is open, so
that the fan shaped blades 304 align with and are physically above
the mating seven baffles 322 in the air inflow guard 324 of the
blower housing 154, allowing for maximum air intake.
Referring to FIG. 24, the control handle 310 has been moved in the
direction of the arrow 326, providing the closed sealed appearance
of the seven baffles 322 in the air inlet itself and the seven fan
shaped blades 312, which together cover the entire circular air
inlet system for the blower, or impeller, 155, substantially
closing off the air supply to the blower, or impeller, 155,
reducing the work it performs and its load on the engine 20,
allowing more engine 20 power to be applied to the trimmer string
24, and so forth as discussed above in connection with FIGS. 18-20.
The control handle 310 can be adjusted to any intermediate position
between a valve fully opened and a valve fully closed position in
basically infinite increments as selected by the operator. Both
types of air control valves disclosed herein can be used
simultaneously on the same lawn care apparatus 10 having a blower
and string trimmer on the same tool. In many trimming applications,
for example, along a fence in a grass yard, blowing debris away is
not needed or desired and in these cases it is beneficial to cut
off the supply of air to the blower, or impeller, 155 or to cut off
the flow through the air outlet duct, or both.
Referring to FIG. 26, the handle housing 144 is rotated is rotated
180.degree. clockwise relative to the drive shaft housing 12, with
the handle housing 144 being loosened prior to rotation, as
indicated by the arrow 328 to move the handle 146 into position for
use by a left-handed operator, moving the handle 146 along the
direction of the arrow 330. The starting position is shown in FIG.
25, in which the debris shield 148 is essentially horizontal and
closer to the operator than the air outlet duct 156.
Referring to FIG. 27, the lawn care apparatus 10 has been moved
into position for use in edging by a left-handed operator, in which
the debris shield 148 is basically vertical and the air outlet duct
is not visible because it is the lowest par of the blower housing
154. This position is achieved by rotating the handle 146 in the
direction of the arrow 332, which rotates the drive shaft housing
12 in the direction fo the arrow 334 so that the rigidly connected
debris shield 148 rotates into the essentially vertical plane
shown. The set screws 214, 216 are loosened to permit rotation of
the handle 146 relative to the drive shaft housing without moving
the drive shaft housing 12 relative to the engine 20 and are
tightened to lock the handle housing 144 146 rigidly onto the drive
shaft housing 12 when the desired orientation of the main housing
body 228 has been achieve.
Referring to FIG. 28, the lawn care apparatus 10 is shown after
being moved into position for left-handed use in the trimming mode,
with the handle 146 on the right-hand side of the drive shaft
housing 12 and the debris shield 148 basically horizontal, which is
the position achieved through the manipulation indicated in FIG.
27.
Referring to FIG. 29, the stop collar disk 205 allows the stem
portion 180 of the handle 146 to be rotated along the directions of
the double-headed arrow 336 through a range of 135.degree. between
the upper stop flange portion 209 and the lower stop flange portion
338, with the stop rod 211 bumping the upper stop flange 209 when
the lawn care apparatus 10 is in the trimming position for a
right-handed person, as in FIG. 9, and bumping against the lower
stop flange 338 when the lawn care apparatus 10 is in the edging
position for a right-handed operator, as shown in FIG. 10.
Referring to FIG. 30, 31, the stem portion 180 of the crank handle
146 includes an upper toggle latch, or trimming latch and stop
member, 340 connected to the housing 144 by the pivoting connection
342 in its center. A channel 344 along the lower surface of the
upper toggle latch 340 includes left side and right side upstanding
walls that serve as stops when butted against by the alien wrench
stop screw 346. The operator can press down on either end of the
upper toggle latch 340 to allow the housing 144 to clear the top of
the set screw 346 and permit rotation of the housing 144 about the
drive shaft housing 12 until another desired position is achieved,
such as the position shown in FIGS. 32, 33 and used for left-hand
operators who are trimming. Similarly, an edging mode toggle latch
and stop member 348 is pivotally connected to the outer surface of
the housing 144 at the pivot point 350. To move the lawn care
apparatus 10 from the trimming to the edging position by releasing
the trimming latch and stop member 340, rotating the housing 144
and then depressing the relevant end of the edging mode toggle
latch and stop member 348 to raise it and to allow the alien wrench
stop screw 344 to enter the edging mode locking channel 352, then
releases the edging mode toggle latch and stop member 348, locking
the housing 344 into the edging mode. The crank handle 146 is also
rotated as described above. If desired, as shown in FIG. 34, the
alien wrench stop screw 344 can be recessed below the outer surface
of the housing 144 to permit full and free rotation of the housing
144 about the drive shaft housing 12 in response to cranking the
handle 146. For any use of short duration, this is the preferred
mode because frictional losses throughout the system will prevent
undesired rotation of the housing 144 relative to the drive shaft
housing 12 in most applications.
Referring to FIG. 35, in an alternative embodiment, the drive shaft
housing 12 and the drive shaft cable 90 have been cut in two at a
point below the lower end 353 of the housing 144, creating an upper
boom section 354 and a lower boom section 356. Protruding from the
lower boom section 356 is a drive shaft square end fitting 358,
mates with the recesses drive shaft socket 360, recessed into the
distal end 361 of the upper boom section 354. The lower boom
section 356 slides inside the lower end of the upper boom section
354 until the drive shaft square end fitting 358 mates with the
recessed drive shaft socket 360. The positioning button 362,
slightly spring biased upward by the spring strip 364 it is
fastened to, with the spring strip 364 in turn fastened to the
lower boom section 356 by the rivet 365, springs into the neutral
locating aperture 366, signifying to the operator that full
engagement of the shaft parts has been achieved and that the
apparatus is in position for trimming by a right-handed user. Then
the operator tightens the clamp adjustment screw 368, in turn
tightening the drive shaft housing clamp 370 and securing the upper
and lower boom sections 354, 356 together firmly in an operating
position.
Still referring to FIG. 35, loosening the clamp adjustment screw
368 allows the operator to substitute a different lower boom
section 356 having a different and perhaps different style of
working head on it, for example, a wire brush cutter or saw, or to
rotate the lower boom section 356 relative to the upper boom
section 354 so as to achieve a different angle between the
operating plane of the working head and the upper boom section 354
and the engine 20. In this connection, it is conventional to rotate
the lower boom section 356 90.degree. clockwise relative to the
upper boom section 354 and to locate the locating button into the
associated 90.degree. rotation locating aperture 372. Preferably,
however, for the reasons detailed above, the lower boom section 356
should be rotated and then relocated with the positioning button
362 set into the 135.degree. locking aperture 374, which is
135.degree. clockwise from the neutral position locating aperture
366, as indicated by the 135.degree. rotation arrow 376. For
left-handed use with a straight shaft tool, the lower boom section
356 is rotated to align with the negative 1350 locating aperture
378, with its location indicated by the negative 135.degree.
rotation arrow 380.
Referring to FIG. 36, there is shown a schematic view of the lawn
care apparatus 10 shown oriented in three dimensional space plotted
on an xyz coordinate system. The center of trimmer string 24 in the
working head 16 is at the origin of the xyz coordinate system 382
and the rotating string 24 rotates in the xy plane, that is, in the
trimming position parallel to the ground. To achieve a rotating
trimming string rotating in the xz plane, that is truly vertically,
the lawn care apparatus must be rotated in three dimensional space
and not rotated merely in a single plane, which is typically done.
Rotation of such tools to date involves rotating the entire tool
about the axis formed by its own drive shaft housing, i.e., in a
polar coordinate fashion treating either end of the drive shaft
housing as the origin. Not only does this rotation lead to an
improper rotation, but it places the engine in an unsatisfactory
orientation in which engine oil may find its way into the
combustion chamber, as previously noted. To achieve the three
dimensional rotation according to the present invention, the middle
of the trimming string 24 is rotated 45.degree. in the xy plane and
simultaneously rotated 90.degree. in the xz plane and these
rotations are additive about the drive shaft housing 12, leading to
a drive shaft housing rotation of 135.degree. and a rotation of the
handle 146 135.degree. about the stem portion 180. Rotation of
objects in three dimensional space is treated in Euler's rotation
theorem, which has been used and adapted to work out the rotational
aspects of the lawn care apparatus 10.
More particularly, hand-held power tools were originally designed
to trim lawns in a two-dimensional xy plane. Then it became more
practical to edge lawns with string trimmers by moving the rotating
string into a vertical plane. As turf grass management has evolved,
landscapers found that edging could be easily done while
transporting a string trimming or brush cutting path. This
discovery led to a significant reduction in the sale of safer
individual power walk-behind edgers and stick edgers that are set
in a two-dimensional vertical position. However, most string
trimmers and brush cutters continue to be set in a two-dimensional
horizontal position even though the handle is designed for trimming
and edging lawns. Utilizing the combined rotational symmetry of
three-dimensional power tool features corrects the two-dimensional
problem.
The most commonly used definition provided for rotational symmetry
was given by the mathematical physicist Herman Weyl. Weyl explains
that objects are said to be symmetrical if one can subject them to
a certain rotational operation and the object appears exactly the
same after the rotational operation as before. Any such operation
is said to be symmetrical. Objects that are turned about a fixed
center to a new position so as to appear exactly the same shape
must therefore possess a center line of rotational symmetry.
Several objects that are on a center line of rotational symmetry
are said to all possess rotational symmetry if mechanical devices
are positioned anywhere on the center line of symmetry; such that
devices known as gears, levers, wheels, or pulleys can adjust or
transform the objects direction of rotational symmetry. A combined
symmetrical transformation of several objects can be accomplished
by rotating all the individual objects about a given point on the
center line of rotational symmetry. Any starting point [x, y, z] of
an object has symmetry if the new transformation point of an object
[x y z]=Rx(A).Ry(A).Rz(A)*[x, y, z]. In three-dimensional space,
Rx(A), Ry(A) and Rz(A) must have a given rotation between 0.degree.
and 360.degree..
In summary, several objects can be rotated in symmetry about a
three-dimensional xyz axes whereby the sum is equal to the xy
horizontal rotation plus the xz vertical rotation. It is common to
rotate objects on outdoor power tools from a particular center of
rotational symmetry. However, most manufacturers do not account for
the extra 1.degree. of xy horizontal rotation for every 2.degree.
of x-z vertical rotation because there are always two planes (xy
and xz) of reflection instead of the single plane (xy) encountered
for trimming. Inconvenient, dangerous consequences sometimes result
from limiting power tool rotational symmetry to two-dimensional
space.
Any rotation can be given as a composition of rotations about three
axes (Euler Rotation Theorem), and thus can be represented by a
matrix operation on a vector through mathematical operations known
to the art.
While the present invention has been described in accordance with
the preferred embodiments thereof, the description is for
illustration only and should not be construed as limiting the scope
of the invention. Various changes and modifications may be made by
those skilled in the art without departing from the spirit and
scope of the invention as defined by the following claims. For
example, a clutch or transmission may be interposed between the
blower and the string trimmer; tools other than a string trimmer,
such as cutting blades, saws or the like may replace the string
trimmer below the blower. Therefore the invention should be
measured by the claims that follow.
* * * * *